The present invention relates to a ball returning system for tennis or golf comprising a ball collection assembly which in turn comprises a screen suspended from a vertical structure and a trough connected to the bottom of the screen in which the balls are received. Balls are returned via a conduit connected to the trough, to a ball propulsion device from whence balls are delivered to a player.
In U.S. Pat. No. 4,575,081, there is disclosed a means of retrieving tennis balls which was useful, particularly during instructional sessions or other practice sessions, either with or without a partner. The prior system utilizes a wire fence as the damping screen which would be loosely hung off of a standard back court fence so as to intercept the balls which then would drop onto a resilient apron and thence roll into a collection trough. The major difficulty that has been experienced with this and similar constructions that have vertically oriented damping screens, lies in the fact that the screens either hang loosely or are stretched in a vertical attitude above the trough and it is this screen orientation that causes the balls to sometimes bounce back onto the court. Generally these devices have aprons or wide troughs and, on occasion, the apron does not always operate to restrict the ball's action sufficiently so that all of the balls will land into the trough. Also many of the balls do not hit the damping screen in a uniform pattern and on occasion will drop directly down into the trough which does not sufficiently damp the ball, the balls bouncing out of the apron and onto the court.
Another suggestion in the prior art that utilizes a loose net as a damper for tennis balls that are driven towards it so that the same could fall into some sort of a trough, is seen, for example in the Hodges patent, U.S. Pat. No. 4,025,071. Balls, however, striking a loose net that is not fastened at the bottom edge, tend to deflect the net to a considerable degree and may not always permit the ball to fall into a collection trough thereunder so that at times, even devices of this nature do not operate with total ball recovery. This result is recognized in the Hartland patent, U.S. Pat. No. 4,456,252, which utilizes a sweep rack to insure that the ball falls into the collection trough after they have been stopped by the net.
There have also been some suggestions in the prior art of moving captured balls in troughs by the use of conveyers as, for example, in the Salansky patent, U.S. Pat. No. 4,621,812, where a tennis ball rides solely upon a helical conveyer, the difficulty with this type of construction lies in the fact that the tennis ball can readily be dislodged from the conveyer. A similar arrangement of a conveyer is seen in a second Salansky published application (PCT WO85/04336-EPO 177,514 of Apr. 3, 1985), where a net is held in tension along its upper and lower edges by a spring loaded frame and the net is attached at the lower edge to a support which in turn supports a ramp with a trough that contains a helical screw means for moving the balls.